Butadiene is a basic chemical component for the production of a range of synthetic rubbers and polymers, as well as the production of precursor chemicals for the production of other polymers. Examples include homopolymerized products such as polybutadiene rubber (PBR), or copolymerized butadiene with other monomers, such as styrene and acrylonitrile. Butadiene is also used in the production of resins such as acrylonitrile butadiene styrene. Butadiene is typically recovered as a byproduct from the cracking process, wherein the cracking process produces light olefins such as ethylene and propylene. With the increase in demand for rubbers and polymers having the desired properties of these rubbers, an aim to improving butadiene yields from materials in a petrochemical plant will improve the plant economics.
Butadiene is produced almost entirely as a byproduct of ethylene plants. As ethylene plants switch from naphtha feedstock to cheaper ethane, the amount of butadiene byproduct decreases. A supply shortage is anticipated. Butadiene is mainly prepared by thermal cracking made of saturated hydrocarbons, usually naphtha being the raw material. On cracking of naphtha, a hydrocarbon mixture of methane, ethane, ethene, acetylene, propane, propylene, propyne, butenes and butadiene. A disadvantage of generation of butadiene by cracking process is formation of larger amounts of undesired coproducts. Generally, the butadiene has to be separated from butynes and other hydrocarbons formed on cracking by distillation or extraction. The production of butadiene in a cracking process inevitably falls, larger amounts of ethene or propene as coproducts. The shift from naphtha cracking to ethane cracking decreases the amount of the byproduct butadiene production. Alternatively, butadiene can be produced from n-butane by catalytic dehydrogenation.
Dehydrogenation of butane to butene followed by butene to butadiene produces hydrogen. The conversion in this process is limited by equilibrium, and positive free energy is formed by dehydrogenation reactions of butane to butene followed by butene to butadiene. The direct dehydrogenation reactions are endothermic and require additional heat input to drive the reaction. Direct dehydrogenation is slightly favorable only at high temperatures of about 700° C. There is also a low butadiene yield by this method, as in the catalytic dehydrogenation of n-butane predominantly 1-butene and 2-butene are formed.
Therefore, there is a need for a new process configuration to produce butadiene in an economical way that does not involve the additional separation processes. There is a need for an improved process for production of increased yields of butadiene.